Suppose there are 100 consumers with identical individual demand curves. When the price of a movie ticket is $8, the quantity demanded for each person is 5. When the price is $4, the quantity demanded for each person is 9. Assuming the law of demand holds, which of the following choices is the most likely quantity demanded in the market when the price is $6?

Assume that coffee and tea are substitutes. When the price of coffee increases

A) the supply of tea increases. B) the demand for tea decreases. C) the demand for tea increases. D) the supply of tea decreases.

If a perfectly competitive firm's marginal revenue is greater than its marginal cost, as it increases its output, its profit ________ and the price it can charge for its product ________

A) increases; does not change B) decreases; falls C) increases; falls D) decreases; rises E) decreases; does not change